Field
Example embodiments in general relate to a fifth wheel trailer lock for preventing a fifth wheel release handle from being operated to unlock a fifth wheel of a load hauler from a load supported by the fifth wheel.
Related Art
Any discussion of the related art throughout the specification should in no way be considered as an admission that such related art is widely known or forms part of common general knowledge in the field.
Fifth wheels are well known hitch assemblies for attaching loads, such as semi-trailers, to load haulers such as tractor units or trucks. The basic design of a fifth wheel allows a tractor unit or truck to haul a far heavier load than is possible with a simple ball or similar hitch mechanism. For one thing, a fifth wheel is designed to be attached to a tractor or truck rearward of its cab and forward of its rear axle so that the weight of the trailer or other load is distributed over the frame of the tractor or truck and is not concentrated on or rearward of the rear axle. For another, a fifth wheel is designed to be rigidly connected to the frame of the tractor or truck, rather than to a bumper or other cosmetic component, and to provide a connection point that is much more rugged and substantial than a simple ball or similar hitch mechanism.
A number of fifth wheel designs exist and are in common use, and a number of companies design, manufacture, and sell fifth wheels, including Jost International, Fontaine Fifth Wheel, Holland and others. Generally, however, the fifth wheels in substantial use today have certain common elements. Typically, they comprise a large, flat plate with a slotted opening facing rearward toward a trailer or other load to be attached. Often the slot is wider at the rearward end and narrower at the forward end to assist in guiding the trailer or other load into engagement with the fifth wheel. The plate is fixedly connected to the frame of a tractor or truck via a connection structure and is generally pivotable with respect to a horizontal plane between a downwardly tilted position for approaching and hitching the trailer or other load and a substantially horizontal position for supporting the weight of the hitched load. A set of spring-loaded jaws or clamps are mounted beneath the plate in line with and accessible through the slotted opening. Typically, the jaws or clamps are located at or near the forward narrower end of the slotted opening. Also typically, an externally accessible release handle is connected to the jaws or clamps by a connecting assembly beneath the flat plate. Depending on the particular design of the flat pate and connecting assembly, the handle may be pulled outward, pushed inward, slid forward, slid backward, or a combination of such movements to open or release the jaws or clamps. The trailer or other load to be hitched typically includes a downward facing plate and a substantial pin called a king pin designed to be engaged and retained by the fifth wheel.
In typical use, the release handle is operated to open the clamps or jaws and the flat plate is placed in the downwardly tilted position. The tractor or truck is then backed up to the trailer or other load so that the king pin engages the slotted opening. As the truck continues to back up the king pin rides up the slot until it engages the spring-loaded jaws or clamps. Upon engagement, the spring-loaded jaws or clamps automatically close on and lock around the king pin. The height of the trailer is then adjusted as necessary so that the plate on the trailer is supported substantially horizontally on the flat plate of the fifth wheel. To unhitch the trailer or other load, the release handle is operated to open the jaws or clamps and the front end of the trailer is raised slightly. Ground supports or landings are then put in place to support the trailer or other load, and the tractor pulls forward so that the king pin disengages from the jaws and slides outward along the slotted opening until free of the fifth wheel.
A potential problem with the fifth wheels in common use is that the release handle can be operated to release the jaws or clamps and thus unlock the fifth wheel from the king pin even when it is not intended for the trailer or other load to be separated from the tractor or truck. This can occur inadvertently, such as where someone has operated the release handle to release the jaws or clamps for a legitimate purpose and then forgotten to relock them. It can also occur intentionally, such as where a vandal has operated the release handle to release the jaws or clamps with the intent to cause damage. In either case, severe consequences can result if the unlocked condition is not discovered and a semi-trailer containing several tons of cargo separates from the fifth wheel while being hauled. The driver of the tractor unit from which the semi-trailer separates, as well as drivers of other vehicles could suffer severe injuries or even fatalities. Alternatively or in addition, severe damage to the tractor, the semi-trailer, the cargo, and other vehicles and property could result.
There is thus a need for a device to lock the release handle of a fifth wheel in place to prevent the intentional or unintentional unlocking of the fifth wheel and potential separation of a trailer or other load from the fifth wheel while underway. There is also a need for such a device that has one or more other favorable attributes, such as being inexpensive to produce, simple to use, easy to install and uninstall, compact, rugged, and resistant to wear and damage from the elements and other sources.
The example embodiments of a fifth wheel trailer lock disclosed herein are directed to addressing the foregoing needs and the foregoing and other problems of the prior art.